Iron silicides grown on Si(100): metastable and stable phases

Abstract

The growth of iron silicides on Si(100) by solid phase epitaxy has been investigated by photoelectron spectroscopies. The different iron silicide phases appearing and their stability ranges have been determined. We have found three different ranges depending on the initial Fe coverage deposited. In the case of large initial Fe coverages (above 16 ML), we have found the subsequent formation of ϵ-FeSi and β-FeSi 2 upon annealing. For initial Fe coverages below 3.4 ML, a phase of 1:1 stoichiometry is formed upon annealing, followed by the formation of a well-ordered metastable phase which we identify with FeSi 2(CsCl). In the intermediate coverage range, while a poorly ordered phase of 1:1 stoichiometry is found for T < 400°C, further annealing gives rise to a mixed silicide layer, composed by several different phases. The composition and thickness of the different films were determined from a quantitative analysis of X-ray photoemission data.